The viability of long-term human habitation of space requires study of the physiological and behavioral effects of the space environment on the human body. While some effects are known from flight studies performed with astronaut subjects, many effects cannot be studied without subjecting astronauts to discomfort or danger. For this reason, studies of the effects of the space environment are routinely performed using animals such as rodents and birds as subjects.
Experimental animals are housed in habitats that provide all life support requirements including food and water. Habitats often have science accommodations provisions for measuring the amount of food and water ingested by the animals, permitting study of the relationship of ingestion to various physiological and behavioral effects. However, it has proven difficult to meter water delivery in space, and a significant amount is spilled. It is even harder to meter ingestion of dry food because of high and variable amounts of wastage of the crumbs.
Habitats may have separated dry food and liquid water delivery systems, or a paste providing both food and water may be delivered from a single system. Paste diets offer to space research the advantages of a single delivery system for both food and water, less waste of both food and water, better control of delivery, better contamination control, and more accurate quantification of food ingestion. However, no satisfactory automated dispenser for paste diets is available.
One paste feeding apparatus for rodents previously developed by NASA is a ground unit that periodically fills a trough for group feeding of animals. This ground unit is not readily adaptable to space vehicle implementation, since it is too bulky, the fluid dynamics of trough filling in micro gravity are not known, and the trough design leaves a large surface area of paste exposed to contamination and to drying, which reduces the ratio of water to food ingested by the animal. In addition, there is no provision to monitor the quantity of food ingested.
A second device, also never deployed in space, is pie-shaped with pie slice-shaped compartments filled with food paste. An opening in the cover that is moved to expose a three day supply of food at one time. This device has the same drawbacks as designs based on troughs.
The Russian Space Agency (RSA) is understood to have tried a series of paste feeder devices based on the trough concept that are generally reputed to be unsuccessful and fraught with severe contamination problems. The designs have evolved to improve bioisolation, and recently the RSA flew a device with several external bladders filled with clean paste that are periodically squeezed by cosmonauts to deliver to the specimens aliquots of food. This device does not provide automatic delivery or quantification of ingestion, and if large aliquots are delivered to minimize crew involvement then uneaten food sits for extended periods and is subject to contamination.
Accordingly, an object of the present invention is to provide a food dispensing system that is suitable for autonomous unattended operation in space vehicles.
Another object of the invention is to provide an automated food dispenser that dispenses individual food servings for each animal individually only at prescribed mealtimes or, alternatively, on demand, and in a prescribed quantity.
A further object of the invention is to store sterilized food in bulk for long periods and to dispense uncontaminated food throughout that period in precisely measured amounts.
An additional object of the invention is to provide an automated food delivery system that is portable, is of simple construction and that permits quick and easy change in schedules and quantities of food and water dispensed.
And an ancillary object is to provide an automated dispenser that can be easily expanded to include dispensing of a variety of consumable substances, including food, medicine and water.
To meet the principal objectives the present invention uses food that has been powdered or minced and mixed with water to form a paste. Paste food provides the most convenient and flexible means of providing the full nutritional needs, including water, of humans and animals. Paste is easily sterilized within its packaging container by irradiation, and then stored for extended durations without danger of microbial spoilage. Many persons have seen news film footage showing astronauts squeezing paste foods from tubes directly into their mouths.
A regimen of food paste offers clear advantages over solid food for animal experimental subjects. Typically less than half the food and water storage volume is required. Food consumption is more accurately determined because there is less waste. Paste can be dispensed to an accuracy of .+-.0.10 gram food per day and .+-.0.3 ml water per day. Food is stored in a reservoir separately from the animal cage, providing bioisolation of the food from animal wastes. The animal's requirements for both food and water can be met by paste composed of the proper ratio of food to water, reducing the number of delivery systems by half and decreasing dispenser cost, volume and complexity of delivery mechanisms.
The need for reliable automated food dispensers for space applications is clear, but terrestrial applications are also applicable to the care and feeding of pet animals. Pet owners who must be absent from home must board their animals with a kennel or veterinarian, have neighbors attend their animal's needs, or travel with their pets, all of which stress the animal. With the effective and reliable automated food dispenser the animal can be regularly fed in its familiar home surroundings, greatly reducing the amount of attention required of neighbors.